/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.solr.update;

import java.io.IOException;
import java.util.List;
import java.util.Vector;

import org.apache.solr.core.PluginInfo;
import org.apache.solr.core.SolrCore;
import org.apache.solr.core.SolrEventListener;
import org.apache.solr.core.SolrInfoMBean;
import org.apache.solr.schema.FieldType;
import org.apache.solr.schema.IndexSchema;
import org.apache.solr.schema.SchemaField;
import org.apache.solr.search.SolrIndexSearcher;
import org.apache.solr.util.plugin.SolrCoreAware;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * <code>UpdateHandler</code> handles requests to change the index (adds,
 * deletes, commits, optimizes, etc).
 * 
 * 
 * @since solr 0.9
 */

public abstract class UpdateHandler implements SolrInfoMBean {
	protected final static Logger log = LoggerFactory
			.getLogger(UpdateHandler.class);

	protected final SolrCore core;
	protected final IndexSchema schema;

	protected final SchemaField idField;
	protected final FieldType idFieldType;

	protected Vector<SolrEventListener> commitCallbacks = new Vector<SolrEventListener>();
	protected Vector<SolrEventListener> softCommitCallbacks = new Vector<SolrEventListener>();
	protected Vector<SolrEventListener> optimizeCallbacks = new Vector<SolrEventListener>();

	protected UpdateLog ulog;

	/**
	 * Called when a SolrCore using this UpdateHandler is closed.
	 */
	public abstract void decref();

	/**
	 * Called when this UpdateHandler is shared with another SolrCore.
	 */
	public abstract void incref();

	private void parseEventListeners() {
		final Class<SolrEventListener> clazz = SolrEventListener.class;
		final String label = "Event Listener";
		for (PluginInfo info : core.getSolrConfig().getPluginInfos(
				SolrEventListener.class.getName())) {
			String event = info.attributes.get("event");
			if ("postCommit".equals(event)) {
				SolrEventListener obj = core.createInitInstance(info, clazz,
						label, null);
				commitCallbacks.add(obj);
				log.info("added SolrEventListener for postCommit: " + obj);
			} else if ("postOptimize".equals(event)) {
				SolrEventListener obj = core.createInitInstance(info, clazz,
						label, null);
				optimizeCallbacks.add(obj);
				log.info("added SolrEventListener for postOptimize: " + obj);
			}
		}
	}

	private void initLog() {
		PluginInfo ulogPluginInfo = core.getSolrConfig().getPluginInfo(
				UpdateLog.class.getName());
		if (ulogPluginInfo != null && ulogPluginInfo.isEnabled()) {
			ulog = new UpdateLog();
			ulog.init(ulogPluginInfo);
			// ulog = core.createInitInstance(ulogPluginInfo, UpdateLog.class,
			// "update log", "solr.NullUpdateLog");
			ulog.init(this, core);
		}
	}

	protected void callPostCommitCallbacks() {
		for (SolrEventListener listener : commitCallbacks) {
			listener.postCommit();
		}
	}

	protected void callPostSoftCommitCallbacks() {
		for (SolrEventListener listener : softCommitCallbacks) {
			listener.postSoftCommit();
		}
	}

	protected void callPostOptimizeCallbacks() {
		for (SolrEventListener listener : optimizeCallbacks) {
			listener.postCommit();
		}
	}

	public UpdateHandler(SolrCore core) {
		this.core = core;
		schema = core.getSchema();
		idField = schema.getUniqueKeyField();
		idFieldType = idField != null ? idField.getType() : null;
		parseEventListeners();
		initLog();
	}

	/**
	 * Called when the Writer should be opened again - eg when replication
	 * replaces all of the index files.
	 * 
	 * @param rollback
	 *            IndexWriter if true else close
	 * 
	 * @throws IOException
	 *             If there is a low-level I/O error.
	 */
	public abstract void newIndexWriter(boolean rollback) throws IOException;

	public abstract SolrCoreState getSolrCoreState();

	public abstract int addDoc(AddUpdateCommand cmd) throws IOException;

	public abstract void delete(DeleteUpdateCommand cmd) throws IOException;

	public abstract void deleteByQuery(DeleteUpdateCommand cmd)
			throws IOException;

	public abstract int mergeIndexes(MergeIndexesCommand cmd)
			throws IOException;

	public abstract void commit(CommitUpdateCommand cmd) throws IOException;

	public abstract void rollback(RollbackUpdateCommand cmd) throws IOException;

	public abstract void close() throws IOException;

	public abstract UpdateLog getUpdateLog();

	/**
	 * NOTE: this function is not thread safe. However, it is safe to call
	 * within the <code>inform( SolrCore core )</code> function for
	 * <code>SolrCoreAware</code> classes. Outside <code>inform</code>, this
	 * could potentially throw a ConcurrentModificationException
	 * 
	 * @see SolrCoreAware
	 */
	public void registerCommitCallback(SolrEventListener listener) {
		commitCallbacks.add(listener);
	}

	/**
	 * NOTE: this function is not thread safe. However, it is safe to call
	 * within the <code>inform( SolrCore core )</code> function for
	 * <code>SolrCoreAware</code> classes. Outside <code>inform</code>, this
	 * could potentially throw a ConcurrentModificationException
	 * 
	 * @see SolrCoreAware
	 */
	public void registerSoftCommitCallback(SolrEventListener listener) {
		softCommitCallbacks.add(listener);
	}

	/**
	 * NOTE: this function is not thread safe. However, it is safe to call
	 * within the <code>inform( SolrCore core )</code> function for
	 * <code>SolrCoreAware</code> classes. Outside <code>inform</code>, this
	 * could potentially throw a ConcurrentModificationException
	 * 
	 * @see SolrCoreAware
	 */
	public void registerOptimizeCallback(SolrEventListener listener) {
		optimizeCallbacks.add(listener);
	}

	public abstract void split(SplitIndexCommand cmd) throws IOException;
}
